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The general idea sounds good. Is it a RPG?

P.S.
If you want more info on the exclusive cards ask.

Well Spellcard Wise...
level one and two can be used in normal form.
Three is usable only in the EX mode and after you leveled the other cards to Max. Level one is usable up to 3 times in one battle, Two is usable 2 times and the third is only during EX mode but if you use it during EX mode, they revert back to normal instead of the full 5 turn duration.(EX mode is gained like an overdrive in FF7.).
The only spell card with 10% knockout is Cataclysmic Barrage and even so, it fails on bosses all the time (damage is still in effect).

As far as shadow monsters, The Three Step attack is the only one with 20% and not counting the shadow guys, there are two bosses who has 10% death and even so, it needs time to charge.

and fighting system would be Turn base with real time (FF8 or even 9).

Regular spells (not spell card format) use a point system i call
"Card Power". Card power effects only normal spells and not the cards.

and regards to EX mode, Some EX mode versions of each character gives that person a special effect. (Marisa casting two spells at once, Remilia leeching health from attacks.

Thanks but once again...Raw idea. No real story or foundation.

((hate not able to edit my posts...))
So it starts with Monday and each spells works like counting the days off.
so Mon>Tuse>Weds>Thurs>Fri>Sat>Sun in order of spells she casts.

More ideas on exclusive versions of spells...
Marisa: The Mini-Hakkero she uses splits into 4 pieces and from each piece, a master spark comes out where in the middle, they form and Omega Spark fires. Multi target.

Reimu: Her orbs surround all mobs and cast a sealing circle and hurts them for a good amount. Most effective on Undead, Demon or even ??? (which it would be called Shadowan).
Also a 5% chance to inflict a effect where if they try to attack Reimu, the chance it would even be pulled off would go down to 50%.

Suika: She takes one huge drink of her Gourd before throwing Danmaku at one person wildly, then she fires three punches and finishes with a lesser version of Missing Purple Power to stomp on him. The damage depends if you use an item with it. (Fruits or drinks either up her damage or add an element to it)

Cirno: Like perfect freeze in the game, it gives foes a Freeze condition but it can't be removed by fire as it is constant on foes for three turns, after they are left with a slow like effect (takes longer to attack). Ice element immune enemies can be affected by this attack.

Remilia: She summons a red moon that heals the party over time and increases Psychical and magical Damage for five turns.
If inside a dungeon, Remilia will increase her evasion by 20% while the Heal over time is in effect.

Sakuya: The ground collapses under the foes and freeze them in mid space, then knives hit them from many directions. (Similar to Renzokuken of FF8 but a bit longer)

Patchouli: Each attack is a different element where after the status effect is random. Ranging from Paralysis to poison.

Yuka: Solar Flare is just her big attack. Sadly it is weakened in caves or inside buildings. outside it is stronger. and like the slow youkai she is...if you try to use her EX mode again, it will not be available till 5 turns pass.

Sanae: The name is for flavor, all it does is give more dodge to allys and haste for a bit. And at rare times you see Kanako Fly through for no reason.

Flandre: 10% chance of death but it hits all monsters for major damage. after, she is unable to act for three turns. The sword she rides in EX mode dissapears in the ground then appears under the enemies, sending many bullets down like a conductor rod, Following one huge explosion and finally the sword shoots up and slams back down, cracking the floor under them in half.(it is the strongest card in game next to Drunk Oni Flurry if you use Beer of Gods, and Omega Spark)

Almost all the good status effects here are 100% immune by bosses.

Aya was going to be playable but sadly i felt like she didn't fit in well and the fact that her shadow version i was making was "OP" in my eyes.

First her shadow fight would begin with her removing all Buffs from your party (like increased damage and speed). Each time one came up she would null it. at normal level she would pull off two to three attacks before you pull one off (fastest in Gensokyo). And she would have 10% more dodging ability than others. Her character would be the fastest if she was added (Reimu replaced that) and her attacks were all about nulling de buffs in one move and be hard to hit.
I could make her slow and add her but then she would not be the "Fastest".